Uses of urea

[ning]

I am wondering something about transamidation with urea.
First, in eleusis's methylamine synthesis, one first step to acetamide is by reacting ethyl acetate with urea. I imagine it works like this:

EtOAc + H2N.CO.NH2 --> H2N.Ac + EtOCO.NH2

If this is the case, ethyl carbamate is formed as a byproduct? This would seem to be useful.

Second, what about the possibility of fusing NaOH with urea? Could it perhaps result in NaNH2?

NaOH + H2N.CO.NH2 --> NaNH2 + NH3 + CO2

But I guess NaOH reacts with CO2, so...dunno. Perhaps since water would be scrupulously excluded, carbonic acid could not be formed and they wouldn't react. Dunno.

Urea is good to scrub up excess NaOCl, etc, so I hear, so it can be used to quench hoffmann rearrangements, etc. True?

What else can urea be used for?

[Nicodem]

NaOH + H2N.CO.NH2 --> NaNH2 + NH3 + CO2
...is wrong

This is what you get:
2NaOH + H2N-CO-NH2 --> Na2CO3 + 2NH3

[Organikum]

With calcium hydroxide and urea + heat under anhydrous conditions you get ammonia from the decomposition of the urea (biuret etc....) and the Ca(OH)2 doesnt react at all.
For this I guess that similar is going to happen with NaOH and urea under anhydrous conditions. As no water was mentioned I guess this was talked about, if aqueous conditions are meant please mention this - it makes another world out of all....

regards
ORG

[Shane_Warne]

With calcium hydroxide and urea + heat under anhydrous conditions you get ammonia from the decomposition of the urea (biuret etc....) and the Ca(OH)2 doesnt react at all.

ORG, so the Ca(OH)2 is there to simply maintain an anhydrous reaction, is that what you mean?

Do you know of any uses for the decompossition products, biuret and cyanuric (and cyanic even) acid, mate?

[Organikum]

I posted this in a thread called "anhydrous ammonia" in methods some time ago.....

The Ca(OH)2 is completely useless in this reaction as I found out    - I first supposed a reaction like the one Nicodem posted would take place but....
....no no nothing.
And yes its end up with cyanuric acid - this can be decomposed further, but the temperatures needed are rather high, 300°C+ ...

[ning]

And from there, you can get cyanic acid/a cyanic acid salt. Or if there's charcoal in the mixture and you heat it more hot, you get cyanide, very useful.

[Shane_Warne]

I posted this in a thread called "anhydrous ammonia" in methods some time ago.....

Yep, I saw that the other day, when doing the same as ning, looking for urea uses; very nice O! There was another one by Aurelius but I didn't have time to go through it.


Well that's right, you can never have too many acids to show off.  


What about letting a concentrated solution of urea hydrolyse to ammonium carbonate?
The carbonate should precipitate out because of it's lower solubility over time, to indicate that it's moving forward.

You could connect a tube from the bottle of the hydrolysis, to a beaker containing dh2O, to collect any NH3 that escapes as NH4OH solution.

The supersaturated carbonate would be nice for preparing NH4Cl.

[ning]

you might as well just hydrolyzed the urea in HCl. That sounds much simpler to me.

Refs on the pseudo-Ritter reaction mentioned above:

Org Syn CV III, 151

http://www.orgsyn.org/orgsyn/prep.asp?prep=cv3p0148

(very awesome reaction in several ways)

{{Other Refs}}

On tertiary alcohols:

USPT 2247495
CR Hebd. Seances Acad. Sci 228; 1949, 1656
Zh. Obshch. Khim. 29; 1959, 174. English version pg. 177
Collect. Czech. Chem. Commun. 41; 1976, 1557
Pesticide Science 55; 1999, 1229

On tertiary alkenes:

Uc. Zap. Azerbajdzansk. Univ. 5; 1958, 47
(Chem. Abstr. 1959, 18860)
USPT 2849488
USPT 2548585
Zh. Org. Khim. 5; 1969, 254 (english 244)

[Shane_Warne]